The present invention relates generally to fire retardants for use in polymer compositions and the like. More particularly, the present invention relates to an ultra-white N,N'-ethylene-bis-(tetrabromophthalimide) composition and to a method for its production.
Fire retardant compositions are performance chemicals that must meet exacting standards to gain acceptance and widespread use in industry. Among requirements for flame retardants, color is of particular importance. For a majority of applications, it is desired that the flame retardant be as white as possible. This enables production of high quality white plastics, but is also important because polymer processors require that colors of end products result from the particular pigment utilized rather than its combination with the color of the flame retardant.
Another important characteristic of flame retardants is purity, for example as can be shown by thermogravimetric analysis. Flame retardant materials that have significant impurities which decompose, volatilize or sublime at polymer processing temperatures can cause undesired color, blowing and other problems in batches into which they are incorporated. Therefore, improved flame retardant materials will also demonstrate stability to higher temperatures in thermogravimetric analysis.
One material receiving substantial attention as a flame retardant is N,N'-ethylene-bis-(tetrabromophthalimide) (EBT). However, acceptance of EBT compositions in industry has severely lagged largely because EBT compositions thus far available have been too yellow.